Process heating is necessary in many industries from electric power production to food canning. Because heating is often ancillary, recovery of waste heat is often beneficial and economical. However, waste heat is often low temperature that is difficult to recover and use.
Fuel cells have been researched for years as a promising alternative to internal combustion engines for automotive transportation. One of the practical limitations of fuel cells is the necessity of providing hydrogen to the fuel cells. It has been proposed that liquid hydrocarbon fuel be processed on board to produce hydrogen to avoid the need for storage of hydrogen. Hydrogen is obtained from hydrocarbon liquid fuel by reforming and/or by partial oxidation. Because both of these are gas phase reactions, it is necessary to vaporize the liquid fuel prior to converting it to hydrogen. Because fuel cells have an exhaust that includes unburned hydrogen, the exhaust provides an opportunity to provide heat for the vaporization of fuel. In certain fuel cell systems, steam may be needed for steam reforming and/or water shift reacting.
Accordingly, there is a need for a small, lightweight and efficient active microchannel heat exchanger, especially for use in a fuel cell power system as a fuel vaporizer and/or as a steam generator.
Further, in chemical processes, many reactions are endothermic, requiring a source of heat to sustain the endothermic reactions. Also in chemical processes, exothermic reactions often require initial heating to initiate the exothermic reaction(s). Accordingly, there is a need for a small, lightweight and efficient active microchannel heat exchanger especially for use in chemical processes.